In recent years, narrower pitches of circuit patterns of circuit boards have been required in the market in order to increase a board density. In parallel with this tendency, a circuit board incorporating electronic components therein is proposed. The circuit board incorporating electronic components, in particular, is required to have a further narrower pitch in circuit patterns.
Japanese Utility Model Publication No. S62-70473 discloses a method of avoiding short circuits in a circuit having a narrow pitch: forming grooves on an insulated board, and then filling the grooves with conductive paste for forming a circuit, thereby avoiding short-circuits. However, this utility model does not teach at all about incorporating electronic components in the board per se.
On the other hand, Japanese Patent Application Non-Examined Publication No. 2001-93934 discloses a method of manufacturing a circuit board incorporating electronic components as follows: First, press-fit an electronic component into insulating resin, and expose electrodes of the component from a flat surface of the opposite side of the resin. Next, print a circuit pattern on the flat surface, thereby coupling the component with the pattern. However, since circuit patterns with narrow pitches are formed on the flat face of the circuit board manufactured by this method, a short circuit tends to occur between the circuit patterns.